Three other men with them managed to escape, but one was left in a critical condition.

More than 24 hours after they first went missing, rescuers discovered the fourth body. The bodies were found in close proximity to one another near where they were working 90 metres below the surface.

Peter Vaughan, Chief Constable of South Wales Police, said: “We’ve tried to bring this safely to its conclusion. Unfortunately the conclusion we have is the one none of us wanted.”

Richard Smith, chief fire officer for Mid and West Wales Fire and Rescue Service, said: “It’s a bit too early to tell whether they would have stood any chance of survival or not …”

The first body was found overnight after divers sent into the mine could only proceed about 30 metres before having to turn back.

Relatives huddled together in a nearby community centre then spent an agonising day hoping in vain for good news.

Prime Minister David Cameron described the tragedy as a “desperately, desperately sad situation”.

“It is clear the emergency services have done everything they can and worked incredibly hard,” he said.

“They haven’t lacked for anything but it is obviously a desperately, desperately sad situation for everyone concerned.

“The anguish of the families obviously is intense, worrying about their loved ones and the news is not good at all.

“There is going to be desperate sorrow in those families and communities as they come to terms with the loss.”

The accident has shocked the tight-knit community in south Wales, once a coal mining heartland but where only a handful of collieries are still operating today following the rapid decline of the industry in the 1970s and 1980s.

Local lawmaker Peter Hain said it was a “stab in the heart” for the community.

“Everybody is rallying round but everybody is traumatised because they have not known this horror now for a generation or more,” he said.